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Re: [RFA]: Merge stack alignment branch
On Thu, Apr 03, 2008 at 11:34:26PM -0700, Andrew Pinski wrote:
>
>
> Sent from my iPhone
>
> On Apr 3, 2008, at 23:23, "Ye, Joey" <joey.ye@intel.com> wrote:
>
>> STACK branch has been created for a while and a bunch of patches to
>> implement stack alignment for i386/x86_64 have been checked in. Now this
>> branch not only can support all stack variables to be aligned at their
>> required boundary effectively, but also introduce zero regression
>> against current trunk. Here is the background information and the patch.
>> Comments and feedback are high appreciated.
>
>
> Why not align the variables that need the extra alignment? This seems
> simpler and gets rid of the need for target specific changes. I already
> posted a patch to do it that way. It was created to support the Cell
> proccesor. We really need variables which have alignment of 128 byte as the
> DMA will only work on memory that is 128 byte aligned if the size is
> greater than or equal to 128. Also it is not the common case that we need
> the extra alignment.
>
Does your scheme work with reload? To support AVX, we need to
align stack to 32byte whenever AVX register is accessed on stack.
That will be a very common case when -mavx is used. But we want
to keep preferred stack boundary, which defines incoming stack
boundary, as 16byte for binary compatibility.
H.J.